src/nsfd.rs

   1 use std::ffi::CStr;
   2 use std::io;
   3 use std::marker::PhantomData;
   4 use std::os::raw::c_int;
   5 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
   6
   7 pub mod ns_type {
   8     pub trait NsType {
   9         const TYPE: libc::c_int;
  10     }
  11
  12     macro_rules! define_ns_type {
  13         ($name:ident, $number:expr) => {
  14             pub struct $name;
  15             impl NsType for $name {
  16                 const TYPE: libc::c_int = $number;
  17             }
  18         };
  19     }
  20
  21     define_ns_type!(Mount, libc::CLONE_NEWNS);
  22     define_ns_type!(User, libc::CLONE_NEWUSER);
  23     define_ns_type!(Cgroup, libc::CLONE_NEWCGROUP);
  24 }
  25
  26 pub use ns_type::NsType;
  27
  28 file_descriptor_type!(RawNsFd);
  29
  30 impl RawNsFd {
  31     pub fn open(path: &CStr) -> io::Result<Self> {
  32         Self::openat(libc::AT_FDCWD, path)
  33     }
  34
  35     pub fn openat(fd: RawFd, path: &CStr) -> io::Result<Self> {
  36         let fd =
  37             c_try!(unsafe { libc::openat(fd, path.as_ptr(), libc::O_RDONLY | libc::O_CLOEXEC) });
  38
  39         Ok(Self(fd))
  40     }
  41
  42     pub fn setns(&self, ns_type: c_int) -> io::Result<()> {
  43         c_try!(unsafe { libc::setns(self.0, ns_type) });
  44         Ok(())
  45     }
  46 }
  47
  48 #[repr(transparent)]
  49 pub struct NsFd<T: NsType>(RawNsFd, PhantomData<T>);
  50
  51 impl<T: NsType> std::ops::Deref for NsFd<T> {
  52     type Target = RawNsFd;
  53
  54     fn deref(&self) -> &Self::Target {
  55         &self.0
  56     }
  57 }
  58
  59 impl<T: NsType> NsFd<T> {
  60     pub fn open(path: &CStr) -> io::Result<Self> {
  61         Ok(Self(RawNsFd::open(path)?, PhantomData))
  62     }
  63
  64     pub fn openat(fd: RawFd, path: &CStr) -> io::Result<Self> {
  65         Ok(Self(RawNsFd::openat(fd, path)?, PhantomData))
  66     }
  67
  68     pub fn setns(&self) -> io::Result<()> {
  69         self.0.setns(T::TYPE)
  70     }
  71 }